JP6807113B2 - Communication system, communication method and communication device - Google Patents

Description

The present invention relates to a communication system, a communication method, and a communication device that communicate by a flooding method.

When a plurality of sensor nodes are arranged to collect data, a broadcast method called flooding using simultaneous transmission has been proposed in order to reduce the power consumption of the nodes and increase the probability of data collection (for example, Non-Patent Document 1). reference).

In the flooding method using simultaneous transmission, when one sensor node transmits data, one or more relay nodes that have received the data transmit the same data in a broadcast manner after receiving the data. The relay node causes simultaneous transmission of wireless signals, and by repeating this multiple times, it is possible to transmit data to the entire wireless communication system. In the flooding method using simultaneous transmission, the same data is transmitted from a plurality of nodes at the same time, and the relay node can decode even if signals are received from a plurality of nodes at the same time. It also has the advantages of not requiring routing, simplifying implementation, and reducing power consumption.

In a similar method, a time slot is assigned to each communication node, the data of the own node is transmitted in the time slot using the flooding method, and the received relay node relays the data in the assigned time slot. There is a method of relaying the data transmitted from the transmitting node by repeating this and finally reaching the data collecting node. (See, for example, Non-Patent Document 2).

Patent Document 1 describes that a packet is transmitted from a source node to a destination node via a relay node, a cyclic redundancy check (CRC) is included in the packet, and the relay discards an undecryptable packet. Has been done.

Japanese Unexamined Patent Publication No. 2008-42911

F. Ferrari et al. , "Efficient Network Flowing and Time Synchronization with Glossy", IPSN'11, 2011 Chao GAO et al. , "Efficient Collection Usage-Interference Flooding in Wireless Sensor Networks", Proceedings of the Institute of Electronics, Information and Communication Engineers Society Conference, 2011_Communications (2), 428, 2011-08-30 Makoto Suzuki, Tomonori Nagayama, Sotaro Ohara, Hiroyuki Morikawa, "Structural Monitoring Using Simultaneous Transmission Flooding", IEICE Journal B, No. 12, pp. 952-960, 2017

A protocol suitable for collecting sensor data, for example, IEEE802.1.5, uses CRC16 for FCS (frame check sequence). By the way, when data is collected by communication by a flooding method using simultaneous transmission, the relay node is configured to transmit the received data at the same timing, so that a large delay during relay is unacceptable. Also, since it is often battery-powered for a long period of time, the relay node should consume as little power as possible. Therefore, the relay node used in the flooding method is required to reduce the time and power required for processing such as generation of an error detection code, and therefore it is desirable to avoid using a long bit length FCS. On the other hand, in the communication by the flooding method, the node close to the transmitting node does not always relay. A relay node at a distance may receive the data, and at that time, depending on the reception conditions, the incorrect data may be decoded as normal data and transmitted to the next node. In addition, since sensor data is often collected by collecting sensor data arranged at a large number of locations over a long period of time at predetermined time intervals, the number of times data transmission errors occur as the amount of data to be transmitted increases. There is a possibility of increasing. Therefore, there is also a demand for using a long bit length FCS having better error detection performance than CRC16.

The present invention has been made in view of the above problems, and is an advantageous technique for improving the detection accuracy of data transmission errors in a wireless communication system that performs communication using a flooding method using simultaneous transmission. The purpose is to provide.

In order to achieve the above object, the present invention is a communication system that communicates between a plurality of communication nodes by flooding using simultaneous transmission, and the plurality of communication nodes are transmission nodes that generate and transmit packets. , A relay node that relays the packet, and a destination node that is the destination of the packet, and the transmission node includes predetermined transmission data, at least a first error detection code for the transmission data, and at least the above. The packet including the transmission data, the timing information corresponding to the timing at which the packet is transmitted, and the second error detection code for the first error detection code is generated and transmitted, and the relay node generates and transmits the packet. A packet is received, error detection is performed based on the second error detection code, the packet is discarded when an error is detected, and the second error detection code is used when an error is not detected. The packet is updated to reconstruct and transmit, and the destination node receives the packet from the transmitting node or the relay node, and performs error detection based on at least the first error detection code. And.

According to the present invention, it is possible to provide an advantageous technique for improving the detection accuracy of data transmission errors in a wireless communication system using a flooding method using simultaneous transmission.

The figure which shows the configuration example of the wireless communication system which concerns on one Embodiment. The functional block diagram of the transmission node which concerns on one Embodiment. The functional block diagram of the relay node which concerns on one Embodiment. The functional block diagram of the sink node which concerns on one Embodiment. A timing diagram showing a communication subslot using the flooding method according to the embodiment. The figure which shows an example of the structure of the packet sent and received by the communication using the flooding method which concerns on one Embodiment. The sequence diagram which shows the flooding slot of the communication which uses the flooding method which concerns on one Embodiment. The flowchart which shows an example of the process executed by the transmission node which concerns on one Embodiment. The flowchart which shows an example of the process executed by the relay node which concerns on one Embodiment. The flowchart which shows an example of the process executed by the sink node which concerns on one Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a block diagram showing a wireless communication system 100 including a relay node according to the first embodiment.

In this example, the wireless communication system 100 includes a transmission node 110 that generates and transmits a packet as a communication node that performs communication, relay nodes 120a to 120f that relay the packet, and a destination node that is the destination of the packet. Here, a sink node 130 that collects data as a destination node will be described as an example.

The transmission node of the wireless communication system according to the present embodiment generates a packet including sensor data and the like at a predetermined timing and transmits the packet. The relay node that receives the packet broadcasts the same packet using the flooding method. By repeating this reception and transmission, the data transmitted from the transmission node 110 is collected at the sink node 130, which is the destination of the packet. Data is transmitted from the transmission node 110, and the relay node 120 relays the data by repeating broadcast transmission using the flooding method. The period during which one cycle is executed from when data is transmitted from the transmitting node to when the relayed data is received by the sink node 130 is called a flooding slot. Within the flooding slot, the time slot in which each communication node transmits or receives is called a subslot.

In FIG. 1, a wireless communication system including one transmission node 110, a plurality of relay nodes 120a to 120f, and one sink node 130 as a destination node will be described as an example, but there are a plurality of wireless communication systems. It may include a transmitting node 110 and a plurality of sink nodes 130.

Further, in the present embodiment, the transmission node 110 and the relay node 120 are described as different communication nodes, but the transmission node 110 may operate as the relay node 120. The relay node 120 can also operate as the transmission node 110. When the communication nodes are arranged as shown in FIG. 1, as shown by the solid line, the case where the packet is transmitted from the transmitting node 110 to the sink node 130 via the communication node having a short distance will be described below. ..

Before the explanation of the communication by the flooding method using the simultaneous transmission between the communication nodes, each type of communication node will be described. Further, in the present embodiment, the transmission node 110 will be described with reference to FIG. 2 by taking the case where the transmission node 110 transmits data from the sensor as an example. The transmission node 110 includes a wireless communication unit 201 including a transmission unit and a reception unit, a communication control unit 202, a schedule management unit 203, a time generation unit 204, a data holding unit 205, and a sensor input unit 207. .. The communication control unit 202 includes a transmission processing unit 2021 and a transfer processing unit 2022. In this example, the sensor 206 is connected to the sensor input unit 207 of the transmission node 110, but the transmission node 110 may include the sensor 206 inside.

The sensor 206 performs predetermined sensing at the installation location and transmits the sensed data to the transmission node 110. The wireless communication unit 201 is a module that operates as a transmission / reception unit for wireless communication, and wirelessly transmits / receives data to / from another relay node 120 via an antenna included in the wireless communication unit 201 or an external antenna (not shown). I do. The communication control unit 202 manages the communication state of the wireless communication unit 201 and causes the transmission / transfer process to be executed according to a predetermined sequence.

The transmission processing unit 2021 of the communication control unit 202 sends the data from the data holding unit 205 to the wireless communication unit 201, and at that time, a first error detection code for the data can be generated and added to the data. .. The transfer processing unit 2022 of the communication control unit 202 receives a packet from another communication node via the reception unit of the wireless communication unit 201, analyzes the data from the other communication node, and broadcasts the received packet. Responsible for relay processing to send. At that time, if an error of the second error detection code included in the packet, which will be described later, is detected, the packet is discarded. Further, the transfer processing unit 2022 changes the timing information described later included in the packet in the relay processing. The data transmitted by the wireless communication unit 201 will be described later with reference to FIG. Further, the wireless communication unit 201 generates a second error detection code for the packet to be transmitted, includes it in the packet, and transmits it. As the first error detection code, a code having better error detection accuracy than the second error detection code may be used. The error detection code is an error detection code of the data link layer, for example, the first error detection code is CRC32, and the second error detection code is CRC16 whose bit length is shorter than that of the first error detection code.

The sensor input unit 207 receives the data from the sensor 206 and sends it to the data holding unit 205. The data holding unit 205 includes a memory that holds the sensor data from the sensor input unit 207 in correspondence with the time. The schedule management unit 203 manages the transmission / reception timing of the transmission node 110. In addition, the schedule management unit 203 holds parameters necessary for flooding communication, such as the flooding slot length, the subslot length, and the maximum number of transmissions in the flooding slot. The time generation unit 204 is a clock and is used for setting the control timing of each processing unit. In the present embodiment, the case where the transmitting node transmits data from the sensor will be described as an example, but the present embodiment is not limited to transmitting data from the sensor. For example, the transmitting node can also transmit information from other information processing devices.

FIG. 3 is a block diagram showing the configuration of the relay node 120. The relay node 120 includes a wireless communication unit 301, a communication control unit 302, a schedule management unit 303, and a time generation unit 304. The communication control unit 302 includes a transfer processing unit 3022.

The wireless communication unit 301, the schedule management unit 303, and the time generation unit 304 of the relay node 120 have the same functions as the wireless communication unit 201, the schedule management unit 203, and the time generation unit 204 of the transmission node 110, respectively. Is omitted. Since the communication control unit 302 of the relay node has the same function as the communication control unit 202 of the transmission node except that it does not have a transmission processing unit, the description thereof will be omitted. The relay node 120 may optionally have the same configuration as the transmission node 110, and may have a function as a transmission node.

FIG. 4 shows a configuration example of the sink node 130. The sink node 130 includes a wireless communication unit 401, a communication control unit 402, a data collection unit 403, a schedule management unit 404, and a time generation unit 405. The communication control unit 402 includes a reception processing unit 4021, a retransmission processing unit 4022, and a synchronization processing unit 4023.

The wireless communication unit 401 is a module that operates as a transmission / reception unit for wireless communication, and transmits / receives data wirelessly via an antenna included in the wireless communication unit 401 or an external antenna (not shown). Further, the wireless communication unit 401 inspects the second error detection code included in the received packet, and if there is an error, discards the received packet. The reception processing unit 4021 determines whether or not the received data is incorrect based on the first error detection code included in the received packet data, and stores the normally received data in the data collection unit 403. When an error is detected in the received data, the retransmission processing unit 4022 generates a retransmission instruction for the transmission node 110 and instructs the retransmission processing unit 401 to retransmit via the wireless communication unit 401. The synchronization processing unit 4023 creates and manages the schedule of the entire system. The schedule management unit 404 manages its own subslot. In addition, the schedule management unit 404 holds parameters necessary for flooding communication, such as the flooding slot length, the subslot length, and the maximum number of transmissions in the flooding slot. The time generation unit 405 is a clock.

The synchronization processing unit 4023 periodically transmits time synchronization packets to each transmission node 110 and relay node 120 in order to create and manage a schedule for the entire system. The sink node 130 uses the packet sent to its own subslot to prompt the other transmitting node 110 and the relay node 120 to synchronize. The time-synchronized packet is relayed by the flooding method like other communications.

In one example, the sink node 130 may optionally have a communication unit for transmitting the collected data to the external device or an interface for connecting to the external communication device. The communication unit may be configured to communicate with a communication network including at least one of a wide area wireless communication network such as cellular communication, a wireless local area network such as Wi-Fi, and a wired network.

Next, with reference to FIG. 5, an example of communication by the flooding method using simultaneous transmission performed by the wireless communication system having the configuration of FIG. 1 will be outlined.

FIG. 5 shows an example of using subslots of each communication node when communication is performed by a route as shown by a solid line in the node configuration of FIG. In this example, the maximum number of transmissions that the communication node can transmit in one flooding slot is specified. Here, it is assumed that the maximum number of transmissions is two. That is, the number of times a communication node can send a packet within the period of one flooding slot is limited to two.

First, in the first subslot 501, the transmitting node 110 transmits a packet. It is assumed that the packets from the transmitting node 110 are received by the relay nodes 120a and 120b. In FIG. 5, TX indicates that the communication node transmits the packet, and RX indicates that the communication node receives the packet.

Here, an example of the packet format transmitted by the transmitting node 110 will be described with reference to FIG.

The source 601 is an identifier indicating the source of the packet. In this embodiment, it is information indicating the transmission node 110. The destination information 602 is an identifier indicating the destination of the packet. In this embodiment, it is information indicating the sink node 130. The transmission data 603 is a payload of the packet, and is information generated based on the sensor data acquired by the sensor 206 of the transmission node 110 in the present embodiment, but is not limited to this. Data from another information processing device may be used as transmission data 603. The packet type 604 is information indicating the type of packet transmitted by the communication node, such as a time synchronization packet, a packet for data, or a sleep packet. The authentication code 605 is information used to verify that the transmitting node 110 is a legitimate transmitting node 110 in the wireless communication system. In this example, the first error detection code 606 is an error detection code generated for predetermined transmission data including at least transmission data 603 among the data from the source 601 to the authentication code 605 in FIG. To do. The timing information 607 is information indicating the timing at which the packet is transmitted, and is, for example, information corresponding to the subslot number in FIG. The second error detection code 608 is an error detection code generated for predetermined transmission data including at least transmission data 603 and timing information among the data from the source 601 to the timing information 607 in FIG. ..

Returning to FIG. 5, communication by the flooding method will be described. When relaying a packet, the relay node 120 inspects the second error detection code 608 included in the packet, and if an error is detected, discards the packet. If no error is detected, the packet is forwarded to the next communication node. At the time of transfer, the relay node 120 does not change at least the source 601 and the destination information 602, the transmission data 603, and the packet type 604. On the other hand, the timing information 607 is changed and transferred. Since the timing information is changed, the relay node 120 regenerates and updates the second error detection code 608, reconstructs the packet, and transfers it to the next communication node. The timing information is changed according to the relay timing in the relay node 120, and the relay node 120 updates the second error detection code at the time of transfer with respect to the data including the changed timing information.

For example, in subslot 501, the transmission node 110 sets "1" in the timing information 607 and transmits a packet. The packet transmitted from the transmitting node 110 is received by the relay nodes 120a and 120b in the subslot 501.

In the subslot 502 next to the subslot 501, the relay nodes 120a and 120b increase the timing information 607 to "2" and transfer the packet. Packets transmitted by a plurality of communication nodes in one subslot have the same data and are synchronized in transmission time, so that they are decoded without any problem even if they collide. Therefore, the relay node 120c receives the packets simultaneously transmitted from the relay nodes 120a and 120b as one packet. Packets from the relay nodes 120a and 120b shall be received by the transmission node 110 and the relay nodes 120c and 120d.

Subsequently, in the subslot 503 next to the subslot 502, the transmission node 110 and the relay nodes 120c and 120d transmit the packets received from the relay nodes 120a and 120b. The transmitting node 110 and the relay nodes 120c and 120d set the timing information 607 to "3" and forward the received packet. Packets from the transmitting node 110 and the relay nodes 120c and 120d shall be received by the relay nodes 120a, 120b, 120e, and 120f, and the sink node 130. At this time, the number of transmissions of the transmission node 110 is the second time, and since the number of transmissions has reached the maximum number of transmissions, transmission is not performed in the subsequent subslots.

Since the relay nodes 120a and 120b that transmitted the packet in the subslot 504 have reached the maximum number of transmissions of 2 times, the relay is not performed in the subsequent subslots. In the subslot 506, the relay nodes 120e and 120f that have received the packets from the relay nodes 120c and 120d set the timing information 607 to "6" and transfer the received packets. Packets from the relay nodes 120e and 120f are received by the sink node 130.

When the sink node 130 transmits a time synchronization packet (time synchronization signal) for time synchronization or the like described later, the sink node 130 transmits each communication node in the same manner as the flooding from the transmission node 110 to the sink node 130. Information is transmitted by flooding to. In this case, the source 601 is set with the identifier of the sink node 130, the destination information is set with information indicating that it is a broadcast, and the packet type is set with information indicating a time synchronization packet.

Further, in this example, in the subslot 501, the relay nodes 120c to 120f and the sink node 130 receive the packet without detecting the packet. Further, also in the subslot 502, the relay nodes 120e to 120f and the sink node 130 are receiving. That is, when the flooding slot starts, the relay nodes 120a to 120f and the sink node 130 perform a reception operation to receive the packet.

Next, an example of the process executed by the wireless communication system according to the present embodiment will be outlined with reference to FIG. 7.

FIG. 7 shows a sequence diagram of processing from the sink node 130 executing time synchronization in the wireless communication system to collecting data from the transmission node 110.

Here, as shown in FIG. 7, the flooding slot is, for example, a period until the time synchronization packet transmitted by the sink node 130 is distributed to the communication nodes in the network when time synchronization is performed. Further, when the transmitting node 110 transmits data, it is also a period allocated for transmission from the transmitting node 110 to the sink node 130. In this way, each flooding slot represents the period of data transfer by flooding. In other words, one flooding slot represents a period (downlink) allocated from the sink node 130 to a series of communications destined for at least one of the transmitting node 110 and the relay node 120. Alternatively, it represents a period (uplink) allocated to a series of communications from at least one communication node of the transmission node 110 and the relay node 120 to the sink node 130.

Flooding-type communication as described with reference to FIG. 5 is used for both uplink and downlink. In the case of downlink, the sink node 130 becomes the transmitting node. In this case, the source 601 of the packet is set with information indicating the sink node 130, and the destination information 602 of the packet is set with information indicating the communication node to be the destination or information indicating broadcast.

The flooding slot 701 is a period during which the sink node 130 transmits a time synchronization packet. During this period, information necessary for time synchronization, for example, time stamp information, is notified to each node in the network by a flooding method to the communication node in the wireless communication system.

In the flooding slot 702, the transmission node 110 having data to be transmitted to the sink node 130 requests transmission of data in which the sink node 130 is set in the destination information 602 at a predetermined timing after time synchronization. To send.

In one example, the transmission node 110 waits for a random time or a random number of subslots generated by using a pseudo-random function as a predetermined timing, and transmits a transmission request packet (transmission request signal). In this case, the transmission node 110 that receives the transmission request packet from the other transmission node before transmitting the transmission request packet relays the transmission request packet from the other communication node and stops the transmission of its own transmission request packet. To do. In this way, in the flooding slot 702, the sink node 130 can grasp the communication node requesting the transmission of data.

Subsequently, in the flooding slot 703, the sink node 130 sets a predetermined transmission node 110 in the destination information 602, and transmits a transmission permission packet permitting transmission in the next flooding slot 704.

Subsequently, in the flooding slot 704, the transmission node 110 designated by the transmission permission packet starts transmission in the flooding slot. That is, the transmitter 601 is set with the identifier of the transmission node 110, the destination information 602 is set with the identifier of the sink node 130, and data is transmitted.

Subsequently, the sink node 130, which determines that the sensor data has been normally received in the flooding slot 704, also transmits the transmission permission to the other transmission nodes 110 in the flooding slot 705. After the flooding slot 706, uplink transmission of sensor data is performed for the number of flooding slots corresponding to the number of transmission nodes 110 permitted to be transmitted by the sink node 130. After that, in the flooding slot N, the sink node 130, which determines that the data collection from all the transmission nodes 110 is completed, transmits a sleep packet (sleep signal) instructing sleep. The communication node in the wireless communication system that has received the sleep packet transitions to the sleep state until a predetermined time after the end of the flooding slot N.

<Generation and addition of error detection code>
Even when the communication node is arranged as shown in FIG. 1, the same packet is sent to the relay node at the timing when the packet transmitted by the transmission node 110 reaches the relay nodes 120a and 120b, as shown by the dotted line in FIG. It may be received at 120c. In that case, an error may occur in the received data due to reasons such as poor reception at the relay node 120c (for example, the S / N ratio is low). Depending on the conditions, the data with this error may be transmitted without the error being detected by the error detection code. Then, erroneous data may be received by the sink node 130. Further, when the relay node 120c transmits erroneous data, the data transmitted by the relay node 120c and the data transmitted by the relay nodes 120a and 120b are different, so that the packets may collide and a burst error may occur. Data having this burst error may be relayed to the sink node 130 without being detected by the error detection code. Therefore, the first error detection code and the second error detection code are used to improve the detection accuracy of data errors.

The operation when the transmitting node 110 transmits a packet to the sink node will be described below with reference to FIG. Here, the case of transmitting sensor data will be taken as an example. The transmitting node 110 receives data from the sensor 206 (S801). The transmission processing unit 2021 sets the source 601 that identifies the transmitting node and the destination information 602 that identifies the destination in the packet. In this example, "data" is set for packet type 604. Further, the data from the sensor is set in the transmission data 603, and the authentication code 605 of the transmission node 110 is set. Then, the first error detection code 606 is generated for the source 601 and the destination information 602, the transmission data 603, the packet type 604, and the authentication code 605 (S802). Here, the target for generating the first error detection code 606 may not be all the data from the source 601 to the authentication code 605 shown in FIG. 6, but may be generated only for the transmission data 603, for example. Next, the transmission node 110 acquires the timing information and sets it in the packet timing information 607. For example, "1" is set in the timing information 607 (S803). Subsequently, a second error detection code 608 for all the data from the source 601 to the timing information 607 is generated and added to the packet (S805), and the packet is transmitted by the flooding method (S806). When generating the second error detection code, for example, the transmission data 603, the first error detection code 606, and the timing information 607 may be used instead of targeting all the data.

The operation of the relay node 120 will be described with reference to FIG. The relay node 120 receives the packet (S901) and inspects the second error detection code 608 contained in the packet (S902). If an error is detected, the packet is discarded and packet reception is restarted. If no error is detected, the packet timing information 607 is updated (S903). For the update, for example, the timing information 607 is incremented by 1 to be "2". Next, a new second error detection code 608 is generated (S904), the packet is reconstructed (S905), and the packet is transmitted by the flooding method (S906).

The operation of the sink node 130 will be described with reference to FIG. The sink node 130 receives the packet transmitted by flooding (S1001). The second error correction code 608 is inspected for the received packet. If an error is detected by the second error correction code 608, the packet is discarded (S1002). If no error is detected, the first error detection code 606 is inspected. If an error is detected, the packet is discarded (S1003). If no error is detected, the received data is stored in the data collection unit 403 (S1003).

It is preferable to use a code having a higher detection accuracy than the second error detection code 608 for the first error detection code 606. For example, since the second error detection code 608 needs to be updated at the relay node 120, the CRC 16 that can be easily implemented in hardware and can be generated in a short time is adopted. If CRC16 is adopted here, the format can be compliant with 802.15.4, so that there are advantages such as being able to use a communication chip compliant with the standard and easily satisfying wireless regulations. A data error between nodes can be detected by the second error detection code 608. The first error detection code 606 is generated at the transmitting node 110, inspected at the sink node 130, and unchanged at the relay node 120. For this first error detection code 606, for example, CRC32 is adopted. Since the CRC 32 is processed only by the transmitting node 110 and the sink node 130, it is possible to improve the accuracy of error detection for data without particularly increasing the relay delay and the power consumption at the time of relaying. The first error detection code 606 and the second error detection code 608 perform double error detection on the data. Therefore, for example, a burst error, which is overlooked by the second error detection code 608, can be detected by the first error detection code 606.

110: transmit node, 120a to f: relay node, 130: sink node

Claims (15)

A communication system that communicates between a plurality of communication nodes by flooding using simultaneous transmission, wherein the plurality of communication nodes are a transmission node that generates and transmits a packet, a relay node that relays the packet, and the packet. Is one of the destination nodes that is the destination of
The transmission node includes predetermined transmission data, at least a first error detection code for the transmission data, timing information corresponding to at least the transmission data and the timing at which the packet is transmitted, and the first error detection code. The packet containing the second error detection code for is generated and transmitted.
The relay node receives the packet, performs error detection based on the second error detection code, discards the packet when an error is detected, and discards the packet when an error is not detected. The error detection code of 2 is updated, the packet is reconstructed and transmitted, and the packet is transmitted.
The destination node receives the packet from the transmitting node or the relay node, and performs error detection based on at least the first error detection code.
A communication system characterized by that. The communication system according to claim 1, wherein the timing information is changed when the relay node relays the packet. The second error detection code is generated for all data in the packet except for the second error detection code.
The first error detection code is characterized in that it is generated for all data except the timing information, the first error detection code, and the second error detection code in the packet. The communication system according to claim 1 or 2. The communication system according to any one of claims 1 to 3, wherein the first error detection code and the second error detection code are error detection codes of a data link layer. The communication system according to any one of claims 1 to 4, wherein the bit length of the first error detection code is longer than the bit length of the second error detection code. A communication method in which communication is performed by flooding using simultaneous transmission between a plurality of communication nodes, wherein the plurality of communication nodes are a transmission node that generates and transmits a packet, a relay node that relays the packet, and the packet. Is one of the destination nodes that is the destination of
The transmission node includes predetermined transmission data, at least a first error detection code for the transmission data, timing information corresponding to at least the timing at which the transmission data and the packet are transmitted, and the first error detection code. To generate and send a packet containing a second error detection code for
The relay node receives the packet, performs error detection based on the second error detection code, discards the received packet when an error is detected, and discards the received packet when an error is not detected. Updating the error detection code of 2 and reconstructing and transmitting the packet,
The destination node receives a packet from the transmitting node or the relay node, and performs error detection based on at least the first error detection code.
A communication method characterized by including. The communication method according to claim 6, wherein the timing information is changed when the relay node relays the packet. The second error detection code is generated for all data in the packet except for the second error detection code, and the first error detection code is the timing information in the packet. The communication method according to claim 6 or 7, wherein the data is generated for all data except the first error detection code and the second error detection code. The communication method according to any one of claims 6 to 8, wherein the first error detection code and the second error detection code are error detection codes of a data link layer. The communication method according to any one of claims 6 to 9, wherein the bit length of the first error detection code is longer than the bit length of the second error detection code. It ’s a communication device,
It includes an input unit into which data is input, a control unit that generates a packet containing the data, a transmission unit that transmits the packet, and a reception unit that receives the packet.
The control unit
When transmitting the data input to the input unit, at least a first error detection code for the data, at least timing information corresponding to the timing at which the data and the packet are transmitted, and the first error detection code. A second error detection code for and is generated, and the packet containing the data, the timing information, the first error detection code, and the second error detection code is generated.
When relaying a packet containing transmission data from another communication device received by the receiving unit, error detection is performed based on a third error detection code included in the received packet, and an error is detected. When the error is not detected, the received packet is discarded, the third error detection code is updated, and the packet is reconstructed .
The third error detection code is generated for at least the transmission data, at least a fourth error detection code for the transmission data, and timing information corresponding to the timing when the received packet is transmitted .
A communication device characterized by that. The communication device according to claim 11, wherein the timing information is changed when the packet is relayed. The third error detection code, the communication apparatus according to claim 11 or 12, characterized in that it is generated for all data except the third error detection code of said packet. The first error detection code, before Symbol second error detection code, said third error detecting code and said fourth error detecting code, claims, characterized in that an error detection code of the data link layer The communication device according to any one of 11 to 13. The bit length of the first error detection code is rather long than the bit length of said second error detection code, the bit length of said fourth error detecting code is longer than the bit length of said third error detecting code The communication device according to any one of claims 11 to 14, characterized in that.